A commercially available Geiger counter as a radioactive measuring instrument can be carried by an unskilled person. If he wishes to use the Geiger counter, he turns on a power switch of the counter. The person can discriminate a radioactive concentration in accordance with click sounds and a reading of the meter.
However, it is very dangerous and inconvenient for an unskilled person to enter into a specific area subjected to a radioactive leakage and to measure a radioactive concentration by carrying the Geiger counter.